Clay Talk

Did some clay collecting over the past few weeks and have started processing it into usable stuff. It’s all pretty much sandstone. I don’t know the technical terms, but I group the sandstone around here from ‘dry’ to ‘waxy’. Meaning when you cut into it with a pick you’ll get a waxy shine on the cut surface, or just flat dry and powdery. With the waxy stuff, you can usually get some good sandy clay from it. The dry stuff is good on it’s own as an additive for augmenting your other clays, especially if they don’t mature and leak, the added sandstone seals them right up, without fluxing them too much (if you stick with the whiter sandstones)

The pictures below are of some of the waxy type sandstone, after it’s been dumped in a jar with water and mixed with a power drill mixer. It melted readily into it’s components, no mashing or pounding was necessary prior to mixing. The first picture shows the finest particles, which I scoop out after agitating and allowing to settle. This is the finest clay with the least amount of iron. I’m not too picky here, so I get a bit of the finest sand at the same time. This makes the clay very nice when trimmed soft, and if I just took the finest particles I’d waste too much of what I dug up.

Next is the picture of what I get after sifting through 20 mesh. This will be useful in this clay body as an additive of some larger particles. Also it can be nice adding to other clay bodies, especially some store bought stuff that may not be so interesting, just remember to test first before you spend a bunch of time on a large batch.

The last bit is what didn’t go through 20 mesh, fairly uniform granules for the most part, with some larger pieces of sandstone left over. This particular stone has some interesting green granules that I’ve never seen before. It seems hard but crumbles reluctantly if you press firmly with your fingernail. This size is good to hang on to, just in case. The last picture is of some of the dry type sandstone after I’ve stamped it in my man powered stamper mill. This is a fairly uniform mix now, and can be added to finer clays to give them tooth and help them mature.

Just in case you’re wondering, I do find clay that is actually clay and use it too. Right above the place where I dug the sandstone from the pics above, there was a 5″thick seam of fairly white (light yellow?) fine clay. This is named Stephen’s Clay, after my friend Stephen who discovered it. Although fine, it’s not a nice plastic clay, but rather the consistency of wheat flour, if you wet it thoroughly. Should make some really nice pots though!


In the Japanese pottery world, the word ‘tsuchiaji’, lit. ‘flavor of the clay’ is a much used term. In the case of Karatsu, even more so, though I wouldn’t be surprised if Japan’s long, rich history of unglazed ceramics is the main reason this term is so important.

Possibly the most distinctive characteristic of Karatsu ware is the clay, and one thing you might notice when looking at the ware is the lack of glaze on the foot. It’s probably safe to say that most potters (in the world) pick up pots and examine the foot first when viewing a pot, because it says a lot about the potter who made it. Most of the Karatsu potters and collectors I know do this, not just to view the carving job on the foot, but also to see the clay that was used.

The clays found in Saga prefecture, including the Kishidake area close to Karatsu, are usually quite large particle, non-plastic clays which contain a lot of sands. Lots of sandstone and coal throughout the area as well. Many potters (modern and historically) use sandstone in their clay body to seal the body, since many of the clays will not mature even at higher temperatures. Not only are many of the clays quite sandy, but in many cases the clay used was actually sandstone, not clay. One contemporary potter uses pounded sandstone for his clay body, and close examination of some old pots has shown that they too might be made of sandstone. One group of researchers travelled to Korea and found a place where similar practices had been utilized for hundreds of years (the name of the place escapes me now). These potters started with sandstone and pounded it in stamp mills. They then seived it into various particle sizes and created their clay body from that. Left over particle sized were used for other purposes such as glaze ingredients, making kiln furniture, etc… so that there was no waste, all of the sandstone was used.

Anyway, the most prized characteristic of many Karatsu clays is effect of ‘chirimenjiwa’ or crepe-like crinkling that occurs when the clay is trimmed soft. This effect is most obvious in the 3rd photo below, top left, in the 3 footrings made of a white, sandy Kishidake clay, from the Hobashira kiln.

In all of the photos below, the pots shown are quite old (400 years give or take). All of the clays have developed a patina over the years and are likely much darker than when they were first fired.


Here are 4 views of my current favorite tea cup. I bought it about 5 months ago from Maruta Munehiko. It’s been fired in his anagama, probably at +-1200C, and has a white slip over a dark clay, covered overall in a thin coat of clear, which shows some fairly small crackle.

Originally this cup was a fairly uniform white with iron spotting and pinholing. Shades of the darker clay could be seen through the slip, but browns and yellows were not present. Below are some pictures of the cup as it is now. On the interior, one can see the ‘amamori’ effect (see previous post) to a great degree. Also, the crackle is greatly accentuated, it was not really visible to the naked eye before I started using the cup.

On the interior and exterior, various shades of browns and yellows, which were not present before, have started to suffuse the surface.

I really have started enjoying this cup much more, the more I use it. I’m really looking forword to what it will look like in the future.


This is the first of a group of posts I’d like to make about the appreciation of Karatsu ceramics. There are some characteristics of Karatsu ware that are unique to them, primarily due to the local clays, but also due to other materials as well as techniques, and firing.

The first of these characteristics is ‘Shinsuisei’, roughly translated as ‘affinity for water’. There are two sides to the meaning of this word. First is the actual physical changes that occur. Karatsu ware, as well as some other Japanese wares, improves with age. For example, a new E-Karatsu (brush decorated) or Muji Karatsu (undecorated) teabowl is a relatively understated piece of pottery to say the least. It is only through years of use that this pot will acquire the patina and lanscape that will make it a truly remarkable piece. It is safe to say that all the most beautiful and interesting Karatsu ware is the result of the process not only of the potter initially creating the pot, but also the far longer process of the pot’s owner using it in daily life. So while the potter creates the vessel itself, the user is equally important in the process of creation, because in a sense, the vessel is continually growing to become a complex thing of simple beauty (if that makes sense).

From the technical side, shinsuisei is the result of clay, glaze and/or slip, and firing. Karatsu clay is very rough, large particle clay for the most part (there are exceptions), and even fired to maturity, often has a high absorbtion. Water, and subsequently the minerals in the water and tannins from the tea will penetrate the bowl through imperfections in the glaze such as crackle, pinholes or stone eruptions. Cracks in old bowls accelerate the process. Also the unglazed feet of Karatsu ware contribute to water penetrating the pot.

The second side of shinsuisei refers to the aesthetic of the ware, ware that is perfectly at home and matched to it’s intended use, which in this case is drinking. Karatsu is very famous among tea implements, and Karatsu guinomi are prized as sake drinking vessels. In both cases, the vessels complement and improve the drinking experience. The kanji for sake (酒) has the same reading as the kanji for water (水). Some aficionados like to point this out when the term ‘shinsuisei’ is mentioned, because it could be taken to mean ‘affinity for sake’, as well as ‘affinity for water’.

In both photos below, you can see where the water has penetrated the vessel and given it a unique character that did not exist when the pot was new. Although a pot for comparison is not pictured, the bare clay surfaces are quite a bit darker than they were when these particular pots came out of the kiln. The chipped surfaces of the top hanzutsu teabowl give a hint as to the original color of the clay. Both bowls are quite changed overall, with the crackle and pinholing accentuate by years of use. The cracks in the hanzutsu teabowl, rather than detracting from the beauty, as they would with a ‘clean’ porcelain piece, accentuate the ‘landscape’ and warmth of the bowl. This effect is called amamori ‘雨漏り’, meaning ‘rain leaking in’.

New garden shed almost finished

This is the new garden shed. 3×2.5×2.5 meters, lots of vertical space for tall stuff, perhaps hang a bicycle or two. Just finished the doors yesterday, lucked out in that they fit pretty well from the first try, just had to plane the top of the right door a bit because it was rubbing the frame. What’s left is the covering of the triangular space with acrylic panels to allow light in.

“How does this relate to Karatsu pots?” you may be asking yourself. Well, all of the garden tools, soil, bicycles, wood, and non clay related stuff that are taking up space in my studio will be moved to the shed, making way for a much needed major re-arranging of pottery space. Yes!

Clay Drying Platform

I finally got off my butt and built a clay drying platform for my recycled slurry and stuff that I bring back from the mountain. It’s made of standard cinderblocks and lined with some canvas. The canvas helps to keep everything fairly even, no dry edges and wet center. Pictured is when I had it with one side cloth, one side without, to see which worked better. The cloth side was the winner, hence the canvas.

Since these pics were taken, I’ve reconstituted about 100kg of clay I got from Nishioka Koju’s supply. It’s a beautiful clay that should make some wonderful pots. If you’ve ever seen any of Koju san’s work, you have an idea of the type of clay. It’s a real treasure that I’ll probably never have again.

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